A container image is a read-only template used to create containers. For example, a container image could contain a complete Ubuntu operating system with required programs and their dependency files installed.
Docker provides a simple way to build new container images or update existing container images. In addition to building container images on your own, you can download container images that others have created.
Container images are classified into:
Internal container images are stored in the container registry provided by CCE. They are uploaded by users and accessible only to image owners.
External images are stored in image repositories provided by a third party. For example, the Docker Hub from Docker Inc. CCE users can download container images from public third-party container registries.